One of the main problems associated with the fight against forest fires is the delay before any action is taken, due in part to the lack of automatic mechanisms which can provide early detection.
Current procedures for the detection of forest fires are, in most cases, based on the use of human means for monitoring zones in which fire is a potential danger and only in rare cases on systems based on directional sensors which can raise the alarm if the level of radiation exceeds a predetermined limit. These systems suffer from a number of drawbacks, for example:
They are unable to process a given observation zone in parallel and in real time. PA1 They are unable to identify and classify the heat sources. PA1 The information generated by the sensor is low quality, above all in terms of spatial resolution. PA1 The information refresh frequency is low. PA1 It is impossible to display the information coming from the sensor to an operator as a real time image on a screen. PA1 As a result of the above the detection efficiency of these systems is reduced in terms of speed of response and the probability of the occurrence of false alarms. PA1 The use of infrared vision cameras as the main observation element for generating thermal images and diurnal vision cameras to help with detection and identification. At each instant the cameras produce two-dimensional information about a scene within the zone assigned to the observatory. PA1 The use of original and specific digital image processing algorithms for detecting the heat sources. This gives improvements in the image, filtering, segmentation, data fusion, correlation, etc. PA1 Displaying the scenes captured by the vision cameras on a monitor such that they can by supervised by an operator. PA1 The use of un-manned observatories of minimum complexity so that they can be transportable and autonomous as far as energy is concerned. This factor also implies greater reliability and reduced cost. PA1 The concentration of the digital processing of the images from the various observatories in one control station which has unlimited space and energy and can therefore be fitted with equipment with higher processing capacity and consumption than in the remote and isolated observatories. This gives greater reliability, easier maintenance and reduced cost.
The European Patent 117162 describes a heat source detection system which is based on an infrared sensor element which makes a circular scan step by step. The occurrence of a heat source is detected by sending the information coming from the sensor to a remote station where, for each point, the intensity of the signal from the sensor is compared with that which was recorded during the previous scan, generating an alarm if a certain limit is exceeded.
The need to displace the sensor mechanically and step by step over each point of the zone being monitored, together with the unidimensional nature of the sensor itself, means that the system is slow, low in resolution and liable to create false alarms.
The patent PCT W091/09390 describes a fire-fighting system based on observatories which are also provided with infrared sensors with the addition of diurnal cameras. Fires are detected at the observatory itself which is therefore more complex and as such less reliable than if carried at a remote control station. The drawbacks associated with using infrared sensors instead of infrared vision cameras are the same as those described with reference to the patent EP117162.